Use the RIT Libraries Catalog to find books on the history of telegraphy and how it impacted the world. If interested in Samuel Morse and his Deaf wife, look up his biography using the library catalog or biography database. Thomas Edison worked as a telegrapher and a few of his earliest inventions were related to telegraphy--the stock ticker and electric vote recorder.
You can use the keywords history and telecommunications to get some resources on this topic. You also can use the keywords telecommunications AND encyclopedia to get background information.